package com.devin.avatar.common.config;

import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;
import java.util.Properties;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

public class PropertiesLoader {
    private static Logger logger = LoggerFactory.getLogger(PropertiesLoader.class);

    private static ResourceLoader resourceLoader = new DefaultResourceLoader();

    private final Properties properties;

    public PropertiesLoader(String... resourcesPaths) {
	properties = loadProperties(resourcesPaths);
    }

    public Properties getProperties() {
	return properties;
    }

    /**
     * 取出String类型的Property，但以System的Property优先,如果都为Null则抛出异常.
     */
    public String getProperty(String key) {
	String value = getValue(key);
	if (value == null) {
	    throw new NoSuchElementException();
	}
	return value;
    }

    /**
     * 取出String类型的Property，但以System的Property优先.如果都为Null则返回Default值.
     */
    public String getProperty(String key, String defaultValue) {
	String value = getValue(key);
	return value != null ? value : defaultValue;
    }

    /**
     * 取出Property，但以System的Property优先,取不到返回空字符串.
     */
    private String getValue(String key) {
	String systemProperty = System.getProperty(key);
	if (systemProperty != null) {
	    return systemProperty;
	}
	if (properties.containsKey(key)) {
	    return properties.getProperty(key);
	}
	return "";
    }

    /**
     * 载入多个文件, 文件路径使用Spring Resource格式.
     */
    private Properties loadProperties(String... resourcesPaths) {
	Properties props = new Properties();

	for (String location : resourcesPaths) {

	    logger.debug("Loading properties file from:" + location);

	    InputStream is = null;
	    try {
		Resource resource = resourceLoader.getResource(location);
		is = resource.getInputStream();
		props.load(is);
	    } catch (IOException ex) {
		logger.info("Could not load properties from path:" + location + ", " + ex.getMessage());
	    } finally {
		IOUtils.closeQuietly(is);
	    }
	}
	return props;
    }
}
